Cardiac Quiz Flashcards
What two factors determine mean arterial blood pressure?
1) CO (HR x SV)
2) SVR
What two factors determine cardiac output?
1) SV
2) HR
CO= SV x HR
The interplay of what 3 factors determine stroke volume?
1) preload
2) afterload
3) contractility
What two factors determine preload?
1) intravascular volume
2) venous tone
* when veins constrict, blood is diverted to the heart
What is the major determinant of intravascular volume?
the amount of sodium in the body
What hormone is most important for controlling intravascular volume?
aldosterone–> controls the Na+
What is the best equation for MAP if you know CO and SVR?
MAP = (CO x SVR)/80 + CVP
*this equation can be manipulated to find other values
Preload is the ________ present in the wall of the left ventricle at the end of diastole (immediately prior to contraction).
tension–> “tightness”–> force
*preload is d\t volume, but is not volume–> it is the tension in the wall
Preload is determined by the _______ of blood in the LV chamber at the end-diastole.
VOLUME–> but it is the tension not volume
Afterload is the _______ in the wall of the heart at the time the ______ valve opens.
tension–> force at the time the aortic valve opens
* “After”load–> after systole starts
Afterload is determined by ___________.
SVR…… SVR= PRESSURE
- the > the SVR, the > the afterload
- afterload is d\t the SVR (pressure) on the other side of the valve but is actually the tension on the wall after systole begins
The _______ the SVR, the _______ the afterload.
> SVR=>afterload
When afterload increases, SV _______.
decreases
When preload increases, SV ________.
increases
The > the ventricular filling (volume), the ________ the preload (tension). What explains this?
greater–> this is d\t Frank Starlings Law of the Heart
Where _____ goes, H2O follows.
sodium
When you hear preload think _______, afterload think _______, contractility think ________.
preload=volume
afterload=pressure
contractility=chemicals (inotropes, CCB’s, etc)
SV= _______ - _______.
EDV-ESV
EF= _____________
EF= (EDV-ESV)/EDV x 100
Contractility doesn’t influence _______, it influences ______.
filling–> it influences emptying
Where does angiotensinogen come from?
the liver
Where does renin come from?
the kidney (JGA); its dumped into the blood and affects angiotensinogen–> Ang1
Where is angiotensin converted enzyme (ACE) primarily found and what does it do?
LUNGS–> converts angiotensin I to II
Anytime you see “-ogen” as in angiotensinogen, think ______.
substrate
How can you easily remember the layers and products of the adrenal cortex?
AG (aldosterone–> zona glomerulosa)
CF (cortisol–> zona fasiculata) (glucocorticoids such as cortisol)
TR (testosterone–> zona reticularis)
*remember–> salt, sugar, sex (aldosterone, cortisol, testosterone)
Given you have filled the heart (preload) and that the aortic valve opens (afterload), can you squeeze better? This is contractility. It is determined by the CHEMICAL environment of the cardiac cell. What are some examples of chemicals that alter contractile function?
ions (calcium and magnesium), oxygen, acids, drugs, hormones
*when contractility increases, the ventricle empties MORE completely and SV increases
What is the difference between concentric and eccentric hypertrophy in relation to the size of the left ventricular chamber?
concentric= no change in the size of the LV chamber eccentric= increased size of the LV chamber
What law has to do with ventricular hypertrophy in response to pressure or volume overload?
law of Laplace
What happens during concentric hypertrophy?
LV wall thickens and chamber size remains same–> results from chronically elevated afterload (coarctation of aorta, chronic aortic stenosis, chronic untreated arterial HTN)
*IHSS is different than concentric hypertrophy b\c size of LV chamber would decrease
What happens during eccentric hypertrophy?
LV wall dilates, thus permitting the chamber to enlarge–> results from chronic requirement to pump large volumes of blood (mitral insufficiency, chronic aortic insufficiency, morbid obesity d\t increased volume)
What does coarctation mean?
“narrowing”
Name the 3 main causes of concentric hypertrophy.
1) coarctation of the aorta
2) chronic untreated HTN
3) chronic aortic stenosis
* pressure challenge on the heart
Name the 3 main causes of eccentric hypertrophy.
1) chronic aortic regurgitation
2) chronic mitral regurgitation
3) morbid obesity (50ml/kg–> but they have a lot of kg!)
* volume overload issue
Easy way to remember Law of Laplace…..?
TP for the rectum
T=p x r
*explains ventricular hypertrophy in response to volume or pressure
What is the x axis on the ventricular pressure-volume loop?
VOLUME
What is the y axis on the ventricular pressure-volume loop?
PRESSURE
If the ventricular pressure-volume loop becomes narrower or wider, what is being changed?
VOLUME
If the ventricular pressure-volume loop becomes taller or shorter, what is being changed?
PRESSURE
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does A represent?
mitral valve opens
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. There is normally a slight increase in pressure right before point B. What does this represent?
atrial kick (~25ml)
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does B represent?
mitral valve closes (“S1” sound– end of diastole, systole begins); EDV–> tension in the chamber is “preload” (all the volume is in and now pressure begins to build)
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does C represent?
aortic valve opens–> afterload d\t SVR (~80 DBP–> highest pressure that was reached before ejecting); ejection begins after point C, so volume begins to fall
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does the peak from point C to D represent?
The SBP (~120mmHg)–> highest pressure that was reached while ejecting
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does point D represent?
aortic valve closes (“S2” sound–> systole ends and diastole begins; also this is the ESV–> this point will show you contractility changes… b\c contractility has to do with the amount of blood ejected…. so if more blood is left, then contractility decreased
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does A-B represent?
diastolic filling; volume increases rapidly and pressure only increases slightly
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does B-C represent?
isovolumetric contraction; no change in volume, pressure builds rapidly
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does C-D represent?
Systolic ejection; increase and then decrease in pressure as volume decreases rapidly
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does D-A represent?
isovolumetric relaxation; no change in volume, but rapid decreases in pressure
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does the volume distance between vertical line A-D and B-C represent?
stroke volume (EDV is point B and ESV is point D
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. At what point does systole BEGIN?
B; because this is when the mitral valve closes…. aortic valve doesn’t open until C
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. At what point does diastole begin?
D; aortic valve closes at this point, but the mitral valve doesn’t open until A
If you have an increase in preload, filling increases. What happens to stroke volume if the ventricle empties to the same level as previously.
stroke volume increases…. b\c it ejected MORE to be able to return to the SAME preload
What is the primary problem with cardiac tamponade? What are the 3 main things effected?
it is primarily a “filling” problem
1) decreased filling
2) decreased pressure
3) decreased squeezing
When end-diastolic volume increases (preload), the left ventricle empties to the previous end-systolic volume. So what is happening to SV?
it increases
*so, know the inverse
When preload increases, SV ________. When preload decreases, SV ________.
preload increases, SV increase
preload decreases, SV decreases
When afterload increases, the heart empties (MORE or LESS) _______ completely; both end-diastolic volume (preload) and end-systolic volume (INCREASE or DECREASE _______ when afterload increases.
afterload increases—> heart empties LESS complete–> EDV and ESV INCREASE when afterload increases
When afterload decreases, the heart empties (MORE or LESS) _______ completely; both end-diastolic volume (preload) and end-systolic volume (INCREASE or DECREASE _______ when afterload decreases.
MORE completely–> EDV and ESV decrease
What visual change is seen in a ventricular pressure-volume loop when giving sodium nitroprusside?
decreased afterload–> PV loop shift down (lower pressures) and to the left (smaller volumes)
When contractility increases, the ventricle empties (MORE or LESS) _______ completely; both end-diastolic volume (preload) and end-systolic volume (INCREASE or DECREASE _______ when contractility increases.
MORE; DECREASE
When contractility decreases, the ventricle empties (MORE or LESS) _______ completely; both end-diastolic volume (preload) and end-systolic volume (INCREASE or DECREASE _______ when contractility decreases.
LESS; INCREASE
If a PV loop change shows an increase in SBP, afterload, and increased SV…. what drug could it be?
digitalis (PDE III inhibitor, so increase in cAMP= better squeeze) or calcium–> because there is an increase in SV!!!
Explain how the pressure volume loop shifts when there is an increase in preload. What interventions cause this?
preload increases–> PV loop shifts to a greater EDV WITHOUT a change in ESV
GIVE FLUIDS
Explain how the pressure volume loop shifts when there is an decrease in preload. What interventions cause this?
preload decreases–> PV loop shifts to a smaller EDV WITHOUT a change in ESV
GIVE diuretic (furosemide) or venodilator (nitroglycerin)
Explain how the pressure volume loop shifts when there is an increase in afterload. What interventions cause this?
afterload increases–> PV loop shifts to > pressures (upward) and to > volumes (rightward)
caused by: drugs that increase SVR and afterload–> phenylephrine
Explain how the pressure volume loop shifts when there is an decrease in afterload. What interventions cause this?
afterload decreases–> PV loop shifts to < pressure (downward) and to smaller volumes (leftward)
caused by: drugs that decrease SVR and afterload–> arterial vasodilators such as nitroprusside and hydralazine (apresoline)
Explain how the pressure volume loop shifts when there is an increase in contractility. What interventions cause this?
increased contractility–> PV loop shifts to higher pressures (upward) and smaller volumes (leftward)
caused by: drugs that increase contractility–> positive inotropes and include digitalis and calcium
Explain how the pressure volume loop shifts when there is an decrease in contractility. What interventions cause this?
decreased contractility–> PV loop shifts to lower pressures (downward) and larger volumes (rightward)
caused by: contractility is decreased in heart failure
What is another name for cardiomyopathy?
IHSS–> idiopathic hypertrophic subaortic stenosis
What is seen in the PV loop of a patient with IHSS or cardiomyopathy?
shift to smaller volumes and larger pressures–> d\t outflow tract obstruction; only IHSS causes this combined shift
What is seen in the PV loop with aortic stenosis?
the concentric hypertrophy allows the LV to generate HIGHER pressures, but the LV volume remains about the same as normal–> MORE pressure is required to open the stenotic valve
What is seen in the PV loop with mitral stenosis?
LV filling is diminished–> PV loop reflects DECREASED preload (reduced filling, but emptying is about the same as normal)–> d\t the stenotic mitral valve… filling is reduced so volumes are LESS and pressure in the ventricle is LESS b\c there is LESS volume
On a PV loop… when the sides are not vertical, it is a _______ problem.
a valve problem
For an aortic valve insufficiency (regurgitation) problem… on the PV loop you can draw an ______. If it is a BIG loop, then it is a _____ problem…. if it is a SMALL loop then it is an ______ problem.
“A” (left side of the loop makes the right side of the “A”); chronic; acute
For an mitral valve insufficiency (regurgitation) problem… on the PV loop you can draw an ______. If it is a BIG loop, then it is a _____ problem…. if it is a SMALL loop then it is an ______ problem.
“M” (the right side of the loop, makes the right side of the “M”); chronic; acute
What are the two primary positive results from giving phenylephrine?
1) increase BP
2) improve coronary perfusion
What are the two primary positive results from giving nitroglycerin?
1) dilate veins
2) decrease venous return
What happens to baroreceptors in response to increased arterial blood pressure?
they are stretched and activated
Afferent action potentials from the baroreceptors of the aortic arch are carried to the brainstem (medulla) centers via the ______ nerve.
vagus
Where are baroreceptors found? (2)
1) carotid sinus
2) aortic arch
Afferent action potentials from the baroreceptors of the carotid sinuses are carried to the brainstem (medulla) centers via the ______ nerve.
Hering’s nerve
An ______ in action potentials to the vagus nerve (from baroreceptor stimulation–> increased arterial BP) causes a _______ in action potentials to the sympathetic nerves.
increase; decrease
An ______ in action potentials to the vagus nerve (from baroreceptor inactivation–> decreased arterial BP) causes a _______ in action potentials to the sympathetic nerves.
decrease; increase
Which baroreceptors are physiologically MORE important and are primarily responsible for minimizing acute BP alterations?
carotid baroreceptors
In regards to the baroreceptors reflex…. activation leads to a ______ in sympathetic activity.
DECREASE; parasympathetic prevails
In regards to the baroreceptor reflex, the efferents are the ____ nerve to the SA node of the heart, and the ________ nerves to the ventricles of the heart and the systemic vasculature.
vagus, sympathetic
_________ is a gaseous substance produced by numerous tissues of the body.
nitric oxide (NO)
Nitric oxide is produced by _______ cells of the ______ wall by ____________.
endothelial cells of the vascular wall by constitutive nitric oxide synthase
What effect does cGMP have on smooth muscle?
causes it to relax
What drugs cause NO to diffuse from vascular endothelial cells into the smooth muscle layer of the vascular wall… activating an enzyme called soluble guanylyl cyclase–> triggering the production of second messenger cyclic guanosine monophosphate… causing the muscle to relax?
1) nitroglycerine
2) Na Nitroprusside
3) Isosorbide dinitrate
What are the two current hypotheses for hydralazine’s action?
1) membrane hyperdepolarizing agent via activation of K+ channels
2) alters intracellular calcium via IP3 receptors
What is the difference in nitric oxide generating circuits for nitroglycerin versus nitroprusside?
In NTG, the nitric oxide is generated by enzymes in venous endothelium but NOT arterial endothelium….. With nitroprusside, it is found in BOTH arterial and venous vascular circuits
*BOTH drugs produce bronchodilation!!
Right heart failure promotes _____ edema and Left heart failure promotes ______ edema.
RHF= systemic edema LHF= pulmonary edema
Name 3 causes of edema formation.
1) increased plasma hydrostatic pressure (from HF)
2) decreased plasma colloid osmotic pressure (hypoalbuminemia–> from liver disease)
3) lymphatic obstruction
What hemodynamic change is MOST important to avoid in the patient with coronary artery disease?
tachycardia–> increase myocardial O2 consumption and may simultaneously decrease oxygen supply
Where is pulse pressure the greatest?
dorsalis pedis–> pulse pressure increases as the arterial pressure waveform passes into more peripheral arterial vessels
The area under the arterial pressure curve divided by _____ yields ______.
TIME; MAP
Goals for regurgitation is to keep it fast, full, and forward. What are the goals for stenosis?
1) maintain low HR–> maintain NSR (b\c it takes more time for the blood to get out d\t the valve not wanting to open)
2) avoid bradycardia b\c the SV is fixed
3) maintain intravascular volume
What is the MOST common cause of LV outflow tract obstruction?
aortic stenosis
What is the normal aortic valve area?
2.5-3.5cm2 (remember 2-4)
At what aortic valve area does severe aortic stenosis occur?
0.8-1.0cm2
At what aortic valve area does critical aortic stenosis occur?
0.5-0.8cm2
What happens to oxygen demand and work of the heart with a stenotic aortic valve?
BOTH increased
What are the classic symptoms of aortic stenosis? (3)
1) dyspnea on exertion
2) angina
3) orthostatic or exertional syncope
With aortic stenosis you can hear a _______ murmur at the _________.
systolic murmur heard at the right second intercostal space with transmission into the neck (over the aortic arch)
Spinals and epidurals are ________ with regurgitation.
OK
Spinals and epidural are ________ with stenosis.
Not OK–> especially if valve area is <1cm2
What is the BEST pressor and induction agent to use with aortic or mitral stenosis?
phenylephrine (d\t its lack of beta activity) and etomidate
As the aortic valve area _____, the pt becomes sicker and the pressure gradient ______.
decreases; increases
________ is a delayed complication of acute rheumatic fever.
mitral stenosis
Remember 2-4-6 for aortic and mitral stenosis…. Why?
normal aortic area 2-4
normal mitral area 4-6
Enlarged left atrium d\t mitral stenosis may apply pressure to the _______ and cause hoarseness.
recurrent laryngeal nerve
What is another name for RV failure?
cor pulmonale (d\t left sided failure)
What are some concerns specific to mitral stenosis?
1) anticoagulation may be needed d\t risk of air emboli from a-fib
2) may need diuretics
A _____ murmur can be heard at the _______ or in the ______ during mitral stenosis.
diastolic heart murmur at the apex or in the axilla
Murmur master: ARDS
Aortic regurg is a diastolic murmur best heard at the sternal border
Murmur master: MRSA
Mitral regurg is a systolic murmur best heard at the apex
Murmur master: MSDA
Mitral stenosis is a diastolic murmur best heard at the apex
Murmur master: ASS Arch
Aortic stenosis is a systolic murmur best heard at the aortic arch
